Warning about legacy interface in future releases

configure.ac

@@ -1395,6 +1395,14 @@ m4_foreach_w([elpa_m4_kind],[real complex],[
         ])
 ])
 
+echo " "
+echo "***********************************************************************"
+echo "*  ELPA 2018.11.001 will be the last release where the old, obsolete, *"
+echo "*  legacy API is enabled by default! In the 2019.05.001 release       *"
+echo "*  the legacy API will be still available (but as default switched    *"
+echo "*  off). With the 2019.11.001 release it will be abolished!	    *"					 
+echo "***********************************************************************"
+echo " "
 echo " "
 echo "***********************************************************************"
 echo "*  This is a the first release candidate of ELPA 2018.11.001.rc1      *"